A savvy traveler must know their limitations, but how does one know when they are not using common sense?

Savvy Defined: Common sense, as described by Merriam-Webster, is defined as beliefs or propositions that most people consider prudent and of sound judgment, without reliance on esoteric knowledge or study or research, but based upon what they see as knowledge held by people "in common". Thus "common sense" (in this view) equates to the knowledge and experience which most people already have, or which the person using the term believes that they do or should have. According to Cambridge Dictionary, the phrase is good sense and sound judgment in practical matters ("the basic level of practical knowledge and judgment that we all need to help us live in a reasonable and safe way").

Whichever definition is used, identifying particular items of knowledge as "common sense" is difficult. Philosophers may choose to avoid using the phrase when using precise language. But common sense remains a perennial topic in epistemology and many philosophers make wide use of the concept or at least refer to it. Some related concepts include intuitions, pre-theoretic belief, ordinary language, the frame problem, foundational beliefs, good sense, endoxa, axioms, wisdom, folk wisdom, folklore and public opinion.

Common-sense ideas tend to relate to events within human experience (such as good will), and thus appear commensurate with human scale. Humans lack any common-sense intuition of, for example, the behavior of the universe at subatomic distances , or of speeds approaching that of light . Often ideas that may be considered to be true by common sense are in fact false.